The structure, organization, activation and plasticity of the erythropoietin receptor

Dimerization of the erythropoietin receptor has long been accepted as the s ingular step in its mechanism of activation. Recent studies have revealed a regulatory process for activation that is dependent on the actual configur ation of the receptor-ligand dimer assembly. This aspect of the receptor su bunit assembly appears to extend to the unliganded receptor, which can dime rize on the cell surface and diminish any spontaneous background signaling in the absence of ligand, This self-recognition, as well as the multiple li gand binding capabilities of the receptor binding site, is consistent with an emerging theme of plasticity in protein-protein and ligand-receptor inte ractions.